1. Field of the Invention
The present invention relates to a heating crucible and a vacuum deposition apparatus using the same, and more particularly, to a vacuum deposition apparatus using an improved heating crucible that prevents scattering of a vaporable material.
2. Description of the Related Art
An electroluminescent (EL) device, which is a spontaneous emission display panel, is attracting attention as a next-generation display panel. An EL device provides a wide viewing angle, an excellent contrast, and a fast response characteristic. EL devices are classified into an inorganic EL device and an organic EL device according to a material that forms an emitting layer thereof. An organic EL device provides high brightness, excellent driving voltage, and a fast response speed, and performs polychromy, compared to an inorganic EL device.
Generally, in an organic EL device, an anode layer of a predetermined pattern is formed on a substrate. Then, a hole transport layer, an emitting layer, an electron transport layer are sequentially formed on the anode layer. A cathode layer is formed on the electron transport layer so as to have cathodes orthogonal to the anode layer. The hole transport layer, the emitting layer, and the electron transport layer are thin organic films made of organic compounds.
To manufacture an organic EL device having such a structure, thin organic films, such as, the hole transport layer, the emitting layer, the electron transport layer, or the like, are formed using a deposition apparatus. The deposition apparatus includes a vacuum chamber whose internal pressure is controlled to be between 10−6 and 10−7 torr, a heating crucible that is installed opposite to a substrate within the vacuum chamber to contain an organic compound, and a heater that is installed at the heating crucible and heats and vaporizes the organic compound.
While it is preferable to have the organic compound vaporize into molecules during a deposition operation, a sudden vaporization may occur within the organic compound during the heating, resulting in the organic compound being vaporized in lumps.
Some of the problems caused by this lump-by-lump basis vaporization are as follows. During the deposition operation, a deposition lump may be attached to an opening of a deposition mask. Accordingly, a material is not deposited on a desired area. This problem continuously occurs unless the deposition mask is replaced, thus hindering a mass production. Also, the deposition material lump may be attached to the substrate, which decreases the evenness of a deposited film. Whereupon a portion of the substrate, on which the deposition material lump is deposited, appears dark upon image display. Furthermore, where a part of an organic compound lump is attached to a nozzle, the organic compound lump is continuously deposited and grown inside the nozzle, consequently blocking the nozzle of the deposition apparatus.
To solve the above problems, Korean Patent Publication No. 2000-54211 discloses a heating crucible for a vacuum deposition apparatus having a net-type curtain installed on an opening through which a heated and vaporized organic compound is discharged. However, the net-type curtain installed on the opening in the heating crucible prevents smooth heat conduction from a heater, such that a foreign material first vaporized from the heating crucible and then deposited on the net curtain is not smoothly vaporized. In addition, it is difficult to install the net curtain within the heating crucible.
A Japanese Patent Publication No. hei 10-195639 discloses a vaporization source having a vaporization crucible that contains an organic vaporization material. An orifice which controls the amount of vaporization of the organic material is installed within the vaporization crucible. Since an organic compound is heated by a heater installed over an outer circumferential surface of the disclosed heating crucible, the organic compound is not evenly heated. In addition, the organic compound cannot vaporize uniformly from the entire portion of the crucible.
A Japanese Patent Publication No. 2000-160328 discloses a heating crucible for evaporating an organic compound, including a main body which contains an organic compound, a heater which is installed around an outer circumferential surface of the heating crucible, and a heat shield layer which is installed around an outer circumferential surface of the heater. A Japanese Patent Publication No. 2000-68055 discloses a deposition source for an organic EL device.